The St. Bernard Dog is a very large breed of dog originally bred for rescue and as a working dog. A full-grown male can weigh between 160 and 240 lb (72.5 / 110+ kg) and the approximate height is 27½ inches to 35½ inches (70 to 90 cm).

Saint Bernards are one of the largest dog breeds. There are two varieties of the breed: the short-haired or smooth-coat variety and the long-haired or rough-coat variety.

Temperament
St. Bernards are gentle, friendly, and generally fond of children. Extremely loyal, this breed is eager to please its owners but due to its size, it is essential that proper training and socialization begin early in life while the dog is still a manageable size. An unruly St Bernard presents a problem for even a strong adult so control needs to be asserted from the beginning. St Bernards will bark at strangers and their size makes them good deterrents against most intruders although their aggression as guard dogs rarely equals breeds designed for that purpose.

Health
The very fast growth rate and the weight of a St. Bernard can lead to very serious deterioration of the bones if the dog does not get proper food and exercise. Many dogs are affected by hip dysplasia or elbow dysplasia. Osteosarcoma (bone cancer) has been shown to be hereditary in the breed.

St. Bernards are susceptible to eye disorders called entropion and ectropion. The FCI standard indicates that this is now a major fault. The breed is also susceptible to epilepsy and seizures, a heart disease called dilated cardiomyopathy, and eczema.

The average life span of a St. Bernard is about 8 years, and some insurance companies will not issue a life insurance beyond 8 years.

History
The ancestors of the St. Bernard are the herding dogs of Swiss and Italian farmers like the Great Swiss Mountain Dog, as well as hunting dogs, rescue dogs and watchdogs. Their history has also been connected with the hospice at the Great St. Bernard Pass. First reports of the dogs' presence at the pass date to the 17th century, and they remained loyal companions to the monks there.

The most famous St. Bernard to save people at the pass was Barry (sometimes spelled Berry), who reportedly saved somewhere between 40 and 100 lives. There is a monument to Barry in the Cimetiere des Chiens, and his body was preserved in the Natural History Museum in Berne.

The classic St. Bernard looked very different from the St. Bernard of today, because an avalanche killed off many of the dogs used for breeding. To further the breed, they crossed the remaining dogs with other dogs, but in the process lost much of their use as rescue dogs. The St. Bernard is among the heaviest and largest dog breeds in the world.

Records
The Saint Bernard is consistently regarded as the heaviest breed of dog in the world. The world's heaviest and largest dog in known history was a Saint Bernard named Benedictine, which weighed 162 kg (357 lbs). Benedictine surpassed Zorba, the largest English mastiff on record, which measured 8 feet, 3 inches long and weighed 343 lb. Although heavier Newfoundland dogs have been reported, Benedictine currently holds the world record for the heaviest dog that ever lived.

Naming
The name "St. Bernard" originates from a traveler's hospice on the often treacherous St. Bernard Pass in the Western Alps between Switzerland and Italy, where the name was passed to the local dogs. The pass, the lodge, and the dogs are named for Bernard of Menthon, the 11th century monk who established the station.

"St. Bernard" was in widespread use until the middle of the 19th century. The dogs were called "Saint Dogs","Noble Steeds", "Alpenmastiff", or "Barry Dogs" before, and in parts of North America, they're still called "Saints".